Conventionally a fuel cell system comprises a fuel cell stack and an external reformer, or an internal reformer. The fuel cell stack comprises a plurality of fuel cells. The reformer reforms hydrocarbon fuel to a hydrogen based fuel suitable for use in the fuel cells in the fuel cell stack.
A problem associated with fuel cells operating with a reformer is that the higher hydrocarbons in the hydrocarbon fuel are not always reformed, or removed, in the reformer and this may subsequently lead to the higher hydrocarbons coking in the fuel cells or other parts of the fuel cell system.
Conventional ways of removing the higher hydrocarbons from the hydrocarbon fuel are complex and require additional reactant streams and are subject to the pressure and the temperature constraints of the fuel cell system.